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Questions and Answers About TB

Glossary of Terms Related to TB

TB disease – an illness in which TB bacteria are multiplying and attacking a part of the body, usually the lungs. The symptoms of TB disease include weakness, weight loss, fever, no appetite, chills, and sweating at night. Other symptoms of TB disease depend on where in the body the bacteria are growing. If TB disease is in the lungs (pulmonary TB), the symptoms may include a bad cough, pain in the chest, or coughing up blood. A person with TB disease may be infectious and spread TB bacteria to others.

BCG – a vaccine for TB named after the French scientists who developed it, Calmette and Guérin. BCG is rarely used in the United States, but it is often given to infants and small children in other countries where TB is common.

Chest x-ray – a picture of the inside of your chest. A chest x-ray is made by exposing a film to x-rays that pass through the chest. A doctor can look at this film to see whether TB bacteria have damaged the lungs.

Contact– a person who has spent time with a person with infectious TB.

Culture – a test to see whether there are TB bacteria in your phlegm or other body fluids. This test can take 2 to 4 weeks in most laboratories.

Directly observed therapy (DOT) – a way of helping patients take their medicines for TB. If you get DOT, you will meet with a health care worker every day or several times a week. You will meet at a place you both agree on. This can be the TB clinic, your home or work, or any other convenient location. You will take your medicines while the health care worker watches.

Extensively drug-resistant TB (XDR TB) - XDR TB is a rare type of TB disease that is resistant to nearly all medicines used to treat TB.

Extrapulmonary TB – TB disease in any part of the body other than the lungs (for example, the kidney, spine, brain, or lymph nodes).

HIV infection – infection with the human immunodeficiency virus, the virus that causes AIDS (acquired immunodeficiency syndrome). A person with both latent TB infection and HIV infection is at very high risk for developing TB disease.

Isoniazid (INH) – a medicine used to prevent TB disease in people who have latent TB infection. INH is also one of the four medicines often used to treat TB disease.

Latent TB infection – a condition in which TB bacteria are alive, but inactive in the body. People with latent TB infection have no symptoms, don’t feel sick, can’t spread TB bacteria to others, and usually have a positive TB test. But they may develop TB disease if they do not receive treatment for latent TB infection.

Multidrug-resistant TB (MDR TB) – TB disease caused by bacteria resistant to two or more of the most important medicines: INH and RIF.

Negative – usually refers to a test result. If you have a negative TB skin test reaction or TB blood test, you probably do not have TB infection.

Positive – usually refers to a test result. If you have a positive TB skin test reaction or TB blood test, you probably have TB infection.

Pulmonary TB – TB disease that occurs in the lungs, usually producing a cough that lasts 3 weeks or longer. Most TB disease is pulmonary.

Resistant bacteria – bacteria that can no longer be killed by a certain medicine.

Rifampin (RIF) – one of the four medicines often used to treat TB disease.

Rifapentine (RPT) – one of two medicines used to treat latent TB infection. .

Smear – a test to see whether there are TB bacteria in your phlegm (sputum). To do this test, lab workers smear the sputum on a glass slide, stain the slide with a special dye, and look for any TB bacteria on the slide. This test usually takes 1 day to get the results.

Sputum – phlegm coughed up from deep inside the lungs. Sputum is examined for TB bacteria using a smear; part of the sputum can also be used to do a culture.

TB skin test – a test that is often used to find out if you are infected with TB bacteria. A liquid called tuberculin is injected into the skin on the lower part of your arm. If you have a positive reaction to this test, you probably have TB infection. Other tests will be needed to find out if you have latent TB infection or TB disease.

TB blood test –a test that uses a blood sample to find out if you are infected with TB bacteria. The test measures the response to TB proteins when they are mixed with a small amount of blood. Examples of these TB blood tests include QuantiFERON®-TB Gold in-Tube test (QFT-GIT) and T-Spot® .TB test.

Tuberculinor PPD – a liquid that is injected into the skin on the lower part of your arm during a TB skin test. If you have TB infection, you will probably have a positive reaction to the tuberculin.